Processing user traffic in a virtualised network

User traffic is processed in a virtualised network. First and second VNFs are initialised in the same network namespace as each other in user space in a host and have access to a shared memory region of the host. The first VNF processes user traffic and the second VNF provides a user plane service in relation to user traffic processed by the first VNF. The first VNF is used to establish a point-to-point, shared-memory interface between the first and second VNFs and is used to classify incoming user traffic. In response to the first VNF determining based on the classifying, that the incoming user traffic is to be subject to the user plane service, the first VNF is used to store the incoming user traffic in the shared memory region of the host to enable the second VNF to provide the user plane service in relation to the incoming trier traffic.